Blading



w. B. FLANDERS.

BLADING.

APPLICATION FILED SEPT. 4,1920.

1 A%&, 242 Patented Aug 1, 1922.

WARREN B. FLANDEE-S, OF ESSING'IDII, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

ineaeaa Application filed. September 4, 1920.

Blading, of which the followingis a specification.

This invention relates to blading for elastic-fluid turbines, and more particularly to that class of blading known as reaction blading' in which the steam expands as it passes through the blades thereby causing an increase in velocity and a consequent fall in pressure.

The object of my invention is to provide means whereby large eilective radial clearances may be obtained between the tips ot the moving blades and the turbine casing and between the stationary blades and the rotor, at the same time reducing the leakage past the ends of the blades to a minimum.

I attain this object by means of the blar ing shown in the accompanyin drawing, in which- Fig. l is an elevation of a single stage showing one row of movable blades attached to the rotor and one row of stationary blades attached to the casing, and Fig. 2 a plan view of the rotor.

Referring to the drawing for a more de tailed description of my invention, 1 indicate a turbine casing 10 in which is mounted a row of stationary reaction blades 11. A similar row of movable reaction blades 12 is mounted in the rotor 13, the two rows of lfilades comprising a single stage of the tur- In the turbine casing 10 adjacent the tips of the movable blades 12 a slot let of L- shape section is machined. Mounted in this slot is a strip 15 of similarsection, preferably made of brass, and cut away to form a sharp edge adjacent the tips of the movable blades 12. The strip 15 is preferably made of fairly short lengths which may be inserted into the slots 14 in each half of the casing and hammered into place.

In the turbine rotor 18, adjacent the tips of the stationary blades 11, a slot 16 is machined which has one side substantially perpendicular to the surface of the rotor and the other side making an angle therewith, as shown. Mounted in this slot is a strip 17 of similar section, preferably made of brass,

Specification of Letters Patent.

BLADING.

Patented Aug. 1, 1Q22.

Serial No. 408,184.

and cutaway to form a sharp edgeadjacent the tips of the stationary blades 11. The strip 17 is made narrower than the slot 16, so that strip 18 may be inserted between the side of the slot and the strip and caulked down to hold it firmly in place.

In the plan view of the rotor shown in Figure 2, the dot and dash line 20 is drawn to indicate the position of the centers of the throats of the nozzles formed between the moving blades on the rotor.

The strip 1. 5 should be set in the turbine casing 10 so that the sharp edgeof the strip adjacent the tips of the blades on the rotor 13 will be directly above the centers of the throats of the nozzles formed between the movable blades 12 as indicated by the dash and dot line 20. In a similar way the strip 17 should be mounted in the rotor 13 so that the sharp edge of the strip is directly below the centers of the throats of the nozzles formed between the stationary blades 11..

After the turbine reaches its full speed, and the rotor and the blades have expanded due to the bun-ease in temperature, and the rotor has warped due to the fact that it cannot be perfectly balanced, there must be sufficient clearance between the stationary blades and the rotor and between the movable blades and the casing to prevent blade rubbings. This clearance must be as small as possible in order to prevent undue leakage of steam past the tips of the blades. The greater the clearance the greater will be the leakage which, of course, cuts down the efficiency of the turbine. Since this clearance of necessity be made as small as possible, it is practically impossible to prevent an occasional blade rub which often is the cause of serious damage to the turbine. If a blade rub takes place, the friction between the blades and the opposing element will generate heat which will cause the blades to expand thereby causing increased rubbingand in turn more heat due to increased friction. This often keeps up until dangerously high temperatures are reached, and the blading is injured.

By providing a strip mounted in the casing adjacent the tips of the movable blades, as shown, the clearance between the movable blades and the casing can be made great enough to eliminate all danger of a blade rub. If any rubbing action takes place at all it will be between the tips of the blades and the sharp edge of the strip, the rubbing surface being so smallas to eliminate the danger from heating due to friction. At

the same time the strip will act to prevent leakage of steam between the tips of the blades and the casing. tween the tips of the blades and the sharp edge of the strip is negligible, the clearance between them can be made smaller than between the tips of the blades and the casing in which no strip is provided. Thus the strip serves a double function notonlyto eliminate the danger of a blade rub but to cut down the clearance and thereby cut down the steam leakage past the tips of-the blades improving the efliciency of the turbine.

In a similar way by providing a strip mounted in the rotor adjacent the tips of the stationary blades as shown by my invention, the clearance between the stationary blades and the rotor can be made great enough to eliminate all danger of a blade rub. Also by providing a strip with a sharp edge, the clearance between the blades and the strip can be made smaller thus cuttingdown the steam'leakage past the tips of'the blades thereby increasing the, efficiency of the turbine.

lVhile'I have shown my invention in but one form, itwill be obvious to those skilled in the art that it isnot so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed there ;upon as are imposed by the prior art or as are specifically set forth in the appended claims. What I claim' is 2- 1. In an elastic-fluid turbine, the combination of rotor blades, a stator, renewable wearing st-rips secured to the stator in line As the friction be with said rows and having sharp edges advj'acent to the blade tips and substantially opposite the centers of the throats of the nozzles formed between adj acen't blades.

2. In an elastic-fluid turbine, thecombination of stationary blades, a rotor, renewable wearing strips secured to the .rotor in line with said rows having sharp edgesjadjacent to the blade tips and substantially opposite the centers o'fthe "throats of the nozzles formed between adjacent blades.

3. In an elastic-fluid turbine, the combination of a moving row of reaction blades and a strip arranged in proximity to the blade tips and located approximately in the plane of centers of the throats of the nozzle passages between the blades. Y i

4. In an elastic-fluid turbine, the combination of a, stator, a rotor, one or more rows of reaction blades carried by the rotor andhaving ample clearance with respect to the stator, and a strip for each of said row or rows of reaction blades carried by the stator, arranged in proximity to the blade tips, and being located'infthe plane of centers of the throats of the nozzle passages defined between the blades; is Y i In an elastic-fluid turbine, the combination of a stator, a rotor, a row of reaction blades carried by the rotor and having the tips spaced from the stator, and a renewable strip of softer metal carried by the stator and having a sharp edge-arranged in close proximity to the blade tips and being located in the plane of centers of the throats of the nozzle passages defined between the blades. t

In testimony whereof, I have hereiinto subscribed my name this 25th day jofAugust, 1920. I a WARREN B. FLANDIERS. 

